The EV-120 is a digital pressure indicator, designed for use in conjunction with a KELLER Series 30 transmitter. Together, these two instruments build a highly precise pressure measuring device. The EV-120 interrogates the Series 30 transmitter and updates the display two times every second. The display shows after turn-on the full-scale pressure range of the transmitter and then the actual pressure reading.

No manual adjustments are required; the EV-120 automatically configures itself to any Series 30 transmitter. Because the pressure is communicated and read in digital format, there are no signal conversion errors.